The present invention is directed generally to a vented closure for a container. The container may be of the type adapted to hold any variety of liquids or even flowable solids. More specifically, the invention is directed to a closure capable of effecting a fluid tight seal on a container, yet permitting the flow of air into and out of the container in response to a differential pressure between the atmosphere inside and outside the container, thereby eliminating such differential.
Differential pressures may exist in one of two ways. Either the pressure inside the container exceeds that outside the container, or the pressure outside exceeds that which is inside. In the former situation, air must be allowed to escape from the container in order equalize the pressures. Conversely, when the pressure outside exceeds the inside pressure, air must be allowed in.
The situation where the pressure outside the container exceeds the inside pressure is most frequently encountered when liquid is being dispensed from the container. As liquid is dispensed, a partial vacuum is created within the container. This partial vacuum is eliminated by allowing air to flow into the container, replacing the volume of liquid which is being dispensed therefrom. If there is no airtight seal on the container, the air will be drawn into the container simultaneously with the dispensing of the liquid. Conversely, if the container has an airtight seal, preventing the flow of air into the container while fluid is dispensed, pressure will not be equalized until dispensing is interrupted, and air is allowed to flow into the container through he dispensing aperture. This prevents an even flow of liquid from the container. In some closed systems, the vacuum created within the container may become so great that further dispensing of fluid from the container is not possible until the vacuum is eliminated. This may require a partial disassembly of the system resulting in lost time and frustration.
The second differential pressure situation is where the pressure inside the container exceeds the pressure of ambient atmosphere. This may be encountered due to some chemical reactions occurring within the container causing gases to be generated. Alternatively, a change in elevation of the container, such as in an airplane cabin, or even the physical movement of the container, such as with carbonated liquids, may cause pressure to build up in the container. The build up in pressure within the container can have various effects depending on the nature of the container and the amount of pressure built up. In one frequently encountered situation the contents of the container, or at least a portion thereof, may be expelled when the container is finally opened. In a far more serious situation, if the pressure builds up sufficiently, the container may rupture causing potentially serious injury to bystanders.
Several prior art venting closures have been invented for containers. The majority of these prior art devices are designed to vent externally. That is, the apparatus will allow gas generally within the container to pass to the outside, but will not equalize a differential existing where the external pressure exceeds the internal pressure. Illustrative of the devices are U.S. Pat. No. 4,828,129 issued to Jonkers, May 9, 1989; 4,765,499 issued to von Reis et al., Aug. 23, 1988; 4,722,450 issued to Mario, Feb. 2, 1988; 4,168,012 issued to Hawkinson, Sep. 18, 1979; 3,409,160 issued to Scott, Nov. 5, 1968; and British Patent No. 486,673 issued to The Parozone Co. et al., Jun. 9, 1938. Another prior art closure, U.S. Pat. No. 4,036,386 issued to Nishioka et al., Jul. 19, 1977, allowed the venting of gas into the container, but made no provision for venting to the outside. Still other closures have allowed venting in both directions, but like those cited above, have not made any provisions for a dispensing means integrated as part of the closure. Illustrative of the last category of devices is U.S. Pat. No. 4,896,789 issued to Federspiel, Jan. 30, 1990; 3,951,293 issued to Schulz, Apr. 20, 1976; and Soviet Patent No. 589,163 issued to Nikitaev et al., Jan. 25, 1978. Additionally, some of the above devices (e.g., Scott) have the limitation that they will not allow venting when the container is upside down, or on its side.
Accordingly, it is a primary objective of the present invention to provide a vented closure which will allow gas to flow into and out of the container in response to a pressure differential, thereby increasing safety.
Another objective of the present invention is to provide a vented closure which will allow gas to flow into and out of the container in response to a pressure differential, while providing a liquid-tight seal, thereby preventing liquid from leaking from the container when it is tipped on its side or upside down.
Another objective of the present invention is to provide a means of dispensing liquid from a container while simultaneously allowing air to flow into the container thereby achieving continuous pressure equalization and an even flow of liquid.
Another objective of the present invention is to provide a closure which is easy to use, inexpensive to manufacture and adaptable to a variety of containers.